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    <title>Document</title>
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<script>
    //创建数值并赋值
    let arr =[23,566,21,542,78];
    console.log(arr[2]);//21
    let arr2 =['tom',34.4,true];
    console.log(arr2[4]);
    arr2[4] = null;
    console.log(arr2[4]);
    console.log('-----------');
    //遍历数组
    console.log(arr.length); //获取数组长度
    for (let i = 0; i < arr.length; i++) {
        console.log = arr[i]; 
    }
    //1.找出数组score中的最大值，并算出这个数组的平均数
    // score = [89,67,59,90,54,77,83,88,5,43,10,68];
    console.log('----------------');
    let score = [89,67,59,90,54,77,83,88,5,43,10,68];
    let max=score[0];
    for (let  i = 0;  i < score.length;  i++) {
        if(score[i] >max){
        max =score[i];
    }
    sum = sum + score[i];
    }
    let avg = sum / score.length;
    console.log ('最大值是：'+max);
    console.log ('平均分数为：'+avg);  
    score[1000]=88;
    console.log(score[1000]);
    console.log(score.length);
    for (let i = 0; i < score.length; i++) {
        console.log (score [i]);  
    }
</script>
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